Antenna system for an ordnance missile



Dec. 18, 1962 R. DE WlTT HUNTOON 3,069,113

ANTENNA SYSTEM FOR AN ORDNANCE MISSILE Filed April 10, 1959 A fi 9 I 4QSCILLATOR 2 DETECTOR 9| INVENTOR.

ROBERT D. HUNTOON ATTORNEY5.

T he

rates tent ANTENNA SYTEM FOR AN ORDNANQE MESSILE Robert De Witt Huntoon,Kensingtcn, Md, assignor t the United States of America as representedby the Secretary of the Navy Filed Apr. it 195d, Ser. No. 365,645 4Gaines, (Cl. 244--14) (Granted under Title 35, US. Code (1952), sec.266) The invention described herein may be manufactured and used by orfor the Government of the United States of America for governmentalpurposes without the payment of any royalties thereon or therefor.

This invention relates to radio antennae, and particularly to the use ofa plurality of antennas on a single ordnance missile as in an antennasystem for radio controlled proximity fuzes.

This application is a continuation-in-part of the application of RobertD. Huntoon, Serial No. 522,287, filed February 14, 1944, and nowabandoned.

The primary objective of the instant invention is to provide improvedpolarized transmitting and receiving antenna means so arranged that thelongitudinal body of the ordnance missile is of metal and forms a partof one of the antenna elements adapted to act as a radiator, while aseparate receiving aerial, also carried by the body, is of suchdirectional characteristics that it does not respond effectively todirect radiation from the transmitting area, but is responsive to energyreflected from the target as the latter is approached.

An object of this invention is to provide a plurality of antennas from asingle ordnance missile to serve as an antenna system forradio-controlled proximity fuzes wherein the body of the ordnancemissile forms at least a part of the radiating system and is polarizedlongitudinally substantially in the direction of travel, while atransversely polarized receiving antenna system is carried by the noseof the missile in such a manner and position that it cannot respondefliciently to the transmitted (longitudinal) radiation, but effectivelyreceives a reflected ener A more important and specific object of thisinvention is to provide an antenna system for a radio-controlledproximity fuze of an ordnance missile that receives by direct coupling alocal signal of the transmitted radiation having the proper magnitudefor mixing, with the reflected signal received to create a beatfrequency for functioning the fuze. A beat will be obtained by mixingthe local and reflected signals since the reflected signals will have afrequency which differs from the local signal (or transmitted signal) bywhere V is the velocity of approach of the missile toward the reflectorfor the transmitted energy and A is the wave length of the transmittedradio energy.

Other objects and many of the attendant advantages of this inventionwill be readily appreciated as the same becomes better understood byreference to the following detailed description when considered inconnection with the accompanying drawing wherein:

FIG. 1 is a side elevational view of a bomb provided with a compoundantenna system constructed and arranged in accordance with the presentinvention; and

FIG. 2 is a view on a larger scale centrally broken away, showing thebomb in side elevation and the antenna means in longitudinal section.

Referring now to the drawing wherein like reference numerals denote likeor similar parts throughout the several views, reference character 1designates the body of a bomb shown of generally conventional form andprovided with fins 2, although it will be apparent that the invention isnot limited to the details of the bomb construction and may in fact beapplied not only to missiles of various forms but to other movingobjects, including those commonly classified under the term vehicle.

' An oscillator 4 Within the bomb body may comprise the source ofradiant energy, and excites the metallic casing longitudinally, beingconnected to the bomb at some optimum point as 6, and the tail cap 7which serves as a counterpoise. The tail cap 7 is carried by insulatingpost 8. Dipole receiving antenna rods 9 and 9' are transversely carriedby the insulating cup 10 attached to the nose, the rods being connectedto the detecting means 12, which is diagrammatically illustrated andmay, as shown, be housed within the cup. The receiving antenna systemthus constituted is not only so polarized that there is minimum pickupof transmitted energy, but also, the receiving system is partiallyprotected by the divergent radiation pattern of the longitudinallyexcited bomb.

Due to the movement of the bomb with respect to the reflector (target),the reflected energy received by the dipole is of a different frequencyfrom the small amount of transmitted energy which the dipole alsoabsorbs. A beat frequency is thus established, providing greaterresponse than would otherwise be possible.

During the time the bomb is in flight, the oscillator 4 will excite thebomb and electromagnetic waves will be radiated from the bomb surface ina pattern directly forwardly of the bomb at an angle to the longitudinalaxis of the bomb. The electromagnetic waves produced by the oscillator 4are radiated in a substantially symmetrical pattern around thecircumference of the bomb due to the currents produced thereon. The bodyof the bomb thus acts substantially as a single radiating anten na alongits longitudinal axis, which is perpendicular to the receiving dipoleelements 9 and 9'. A typical radiation pattern of the desired forwarddirected variety may be produced by using the body of the bomb as a longradiating antenna, that is, having an effective length of several wavelengths, and illustrated by the radiation pattern 15 in FIG. 1. Thisforwardly directed pattern 15 would be essentially conical in shape andhave a polarity on opposite sides of the bomb as indicated by thepolarity vectors 13 and 14. It may be seen from these polarity vectors13 and 14- that only a small component thereof 13' and 14 is polarizedsuch as to be received by the dipoles 9 and 9 and that these components13 and 14' are opposite in phase. The major portion of the transmittedenergy 13" and 14 in the vicinity of the dipole elements is crosspolarized with respect to the dipole elements. If the radiation patternof the bomb were perfectly symmetrical, and if the dipoles 9, 9' wereperfectly constructed, the receiver 12 would not receive a signaldirectly from the bomb radiation even though the radiation would bereceived by antenna-rods 9 and 9'. In this case, the energy received bythe two sides of the dipole would cancel out. Actually the wave patternis not exactly symmetrical due to small irregularities in the body ofthe bomb and the unequal excitation of certain portions thereof, and therods 9 and 9' are not exactly alike so that under operating conditions,the receiver 12 will receive a signal of the same frequency as thatradiated from the bomb but of reduced amplitude.

As the projectile approaches the target, the energy radiated by the bombwill be reflected by the target and a portion of this reflected energywill be picked up by the antenna rods 9 and 9. Since the bomb is movingrelative to the target, the frequency of the reflected energy will bedifferent from the frequency pickup by antenna rods 9 and 9' directlyfrom the bomb radiation. A beat frequency will therefore result in thedipoles 9, 9 which can be detected by detecting means 12 in order totrigger the missile.

It is desirable that the amplitude of the wave energy received directlyfrom the bomb be two to three times greater than the amplitude of thereflected wave in order that the beat frequency can be properlydetermined by detecting means 12. The amplitude of the energy receiveddirectly from the bomb can be adjusted, as will be apparent to thoseskilled in the art, by purposely varying the imperfections of thedipoles 9, 9, i.e. either of the antenna elements 9 or 9 may be madeslightly longer than the other thus extending a greater portion thereofinto the radiation pattern to receive a greater amount of the likepolarized component of the transmitted energy, or the composition of onemay be slightly different from that of the other thus changing theeffective impedance.

thereof allowing only a different amount of power to be received by thedetector 12, etc.

A novel wave transmitting and receiving system for a missile is thusprovided whereby a beat frequency can be developed from the reflectedfrequency and transmitted frequency. The substantially symmetricalradiation pattern from the bomb makes possible the reception of thetransmitted frequency at a reduced amplitude by the dipole on the noseof the projectile. The reception of the transmitted wave at reducedamplitude is also aided by the fact that the pair of dipole arms willnot be perfectly symmetrical about the bomb axis due to errors inpositioning or to a difference in length between the two arms. Since theamplitude of the transmitted energy received by the dipole is of thesame order as the amplitude of the reflected energy received by thedipole, a beat frequency can be detected for operation of the fuze.

Obviously many modifications and variations of the present invention arepossible in the light of the above teachings. It is therefore to beunderstood that within the scope of the appended claims the inventionmay be practiced otherwise than as specifically described.

What is claimed as new and desired to be secured by Letters Patent ofthe United States is:

1. An ordnance missile having a radio-proximity fuze comprising anelongated metallic body, a source of high frequency waves, meansconnecting said wave source to said body whereby said body acts as awave transmitter having a radiation pattern projecting forwardly of saidbody at an angle to the longitudinal axis thereof, a dipole mounted onthe forward end of said metallic body in an unsymmetrical position withregard to the radiation pattern of said transmitter to receive a firstradio signal directly from said transmitter at reduced amplitude, saiddipole receiving a second radio signal reflected from a target at afrequency different from the transmitted frequency, and a detectingmeans electrically connected to said dipole to produce a beat frequencyfrom said first and second radio signals.

2. An ordnance missile having a radio-proximity fuze comprising anelongated metallic body, a source of high frequency waves, meansconnecting said wave source to said body whereby said body acts as awave transmitter having a radiation pattern projecting forwardly of saidbody and at an angle to the longitudinal axis thereof, a dipole mountedon the forward end of said metallic body Within the radiation pattern ofsaid transmitter, the arms of said dipole being dissimilar in order toreceive a first radio signal directly from said transmitter at reducedamplitude, said dipole receiving a second radio signal reflected fromthe target at a frequency different from the transmitted frequency, anda detecting means electrically connected to said dipole to produce abeat frequency from said first and second radio signals.

3. An ordnance missile having a radio-proximity fuze comprising anoscillator and an elongated metallic body acting as a transmitter forradio energy, said metallic body having a radiation pattern projectingforwardly of said missile at an angle to the longitudinal axis of saidmissile, said radiation pattern being slightly unsymmetrical about saidlongitudinal axis, a dipole antenna mounted within said radiationpattern on the forward end of said metallic body with its armsapproximately symmetrical about said longitudinal axis, a first radiosignal of transmitted frequency and reduced amplitude received by saiddipole as a result of the non-symmetry of said radiation pattern, asecond radio signal of frequency different from said transmittedfrequency reflected from a target and received by said dipole, and adetecting means electrically connected to said dipole for producing abeat frequency from said first and second signals to trigger saidmissile. 4. An ordnance missile having a radio-proximity fuze comprisingan elongated metallic body acting as a transmitter for radio energy, anoscillator electrically connected to said metallic body and to acounterpoise insulated from said metallic body to supply energy to saidietallic body, said metallic body having a radiation pattern projectingforwardly of said missile at an angle to the longitudinal axis of saidmissile, said radiation pattern being somewhat unsymmetrical about saidlongitudinal axis, a dipole antenna mounted on the forward end of saidmetallic body within the radiation pattern of said transmitter, the armsof said dipole being positioned transverse to said longitudinal axis andbeing dissimilar, a first radio signal received from said transmitter ata reduced amplitude as a result of the unsymmetrical radiation patternand the dissimilarity of said dipole arms, a second radio signal offrequency different from the transmitted frequency reflected from atarget and received by said dipole, and at detecting means electricallyconnected to said dipole for producing a beat frequency from said firstand second radio signals to trigger said missile.

References Cited in the file of this patent UNITED STATES PATENTS2,311,435 Gerhard Feb. 16, 1943 2,629,865 Barker Feb. 24, 1953 2,645,769Roberts July 14, 195.3

FOREIGN PATENTS 91,592 Sweden Feb. 24, 1938 OTHER REFERENCES Huntoon etal.: Generator-Powered Proximity Fuze, Electronics, pp. 98-103, December1945.

